This invention relates in general to casting molds or other equipment and in particular to a method and apparatus for monitoring separation distance of two surfaces such as casting molds in a hostile environment such as high heat, smoke, dirt, oil mist, and sprays.
A casting mold is used to make various cast articles out of various materials. The casting mold typically includes two or more mold sections, such as for example a lower mold section and an upper mold section. When the lower mold section and the upper mold section are placed together in an abutting relationship, they cooperate to define a mold cavity. The mold cavity is generally in the shape of the cast articles to be produced. When the lower mold section and the upper mold section are placed together, a suitable molten or liquid fill material, such as for example, metal or plastic, is provided to fill the cavity and produce the cast article. Preferably, the fill material does not leak or seep out from the mold cavity as the fill material cools. Once sufficient cooling has occurred, the lower mold section and the upper mold section are separated from each other to enable the cast article to be removed.
The fill material used with the casting mold is typically obtained in a solid state, then heated to a liquid or molten state. The fill material may be heated in a furnace or other suitable apparatus. The fill material can leak (spill) from the mold cavity if the lower mold section and the upper mold section do not reach the desired separation or do not otherwise properly close together so as to define a sealed or closed mold cavity chamber. Depending on the particular molding process, it may be desirable for the two surfaces to come in contact (as with permanent metal molds) or to obtain a predetermined separation distance (as with sand molds).
Such leaks of the fill material are undesirable and can occur because one or both of the mold sections have become misshapen, misaligned, or do not totally close due to presence of dirt or flash, loss of hydraulic pressure, or inadequate lubrication. The resulting spill or leakage can be devastating to nearby components such as electrical wiring, hydraulic lines, coolant lines, limit switches, etc. Thus, it would be desirous to provide an improved method and apparatus for a casting mold that can be used so as to determine the relative positions of the mold sections before filling with molten metal.
This invention relates to a method and apparatus for monitoring a casting mold or other equipment to determine if the mold sections are properly closed in a sealing relationship. In a preferred embodiment, the distance between two surfaces is determined using the flow of pressurized air from a chamber through a first orifice into a pipe and then through a second orifice in one surface toward the other surface. The pressure drop between the chamber and the pipe is measured and quantifies the separation distance. For example, if the surfaces have a large separation distance then the second surface will not restrict the air flow and the pressure measured in the pipe will be approximately atmospheric pressure. As the surfaces approach one another, the pressure measured in the pipe will rise following a curve that can be determined empirically. When the surfaces come in contact, the pressure in the pipe will have risen to the pressure in the pressurized chamber. Thus, a reliable and accurate distance can be measured in extremely high temperature, smoky, or dusty environments. Other advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings.